The Telecommunications Management Network ("TMN") is a network providing for the transport, storage and processing of information to support management of telecommunication networks and services and is an organized architecture capable of achieving interconnections between various types of Operations System and/or telecommunications equipment. As described in the M.3000 series of recommendations from the Telecommunications Standardization Sector of the ITU (ITU-TS, formerly CCITT), and, in particular, recommendation M.3010 entitled "Principles for a Telecommunications Management Network," CCITT Com IV-R 28, Sect. 11.1, November 1991, incorporated by reference as if fully set forth herein, TMN is said to be "the general architectural requirements . . . to support the management requirements . . . to plan, provision, install, maintain, operate and administer telecommunications networks and services".
Pursuant to ITU-T (X.700), one broad TMN function is Configuration Management which, provides for the control over the configuration of the telecommunications network components and particularly, 1) the provisioning of circuits and paths, managing restoration of circuit and paths, 2) the monitoring end-to-end performance, 3) the locating of faults and, 4) the maintenance of network elements connectivity. Configuration management provides hardware and software necessary to, inter alia, collect and disseminate data concerning the current state of telecommunication network resources, set and modify parameters related to network components, initialize and close down resources, and change the configuration.
One Configuration Management function implies the rearranging of current network bandwidth configuration to enhance network adaptability to both expected and unexpected traffic variations. In TMN, execution of bandwidth management may involve, e.g., rearranging VP bandwidth when a reconfiguration control parameter, such as, e.g., VP use, or when network traffic exceeds a predefined threshold.
Pursuant to TMN requirements, the SDH and SONET (Synchronous Optical NETwork) transmission schemes have been standardized to provide a layered transport network architecture. For purposes of description, a layer is defined as a set of points of the same kind that can be interconnected due to the very same nature of the signal carried. As shown in FIG. 1, for SDH (SONET), the functional architecture 40 is composed of three layers: the circuit layer 47, path layer 48, and transmission media layer 49 [ITU-T G. 805, 1992]. The circuit layer networks 47 provide telecommunication services such as circuit-switched, packet-switched, and leased-line service and is the end-to-end connection established/released either dynamically or by short-term provisioning. The transmission media network 49 is the layer that interconnects nodes and is the physical connection based on long-term provisioning. This layer may be divided into section layer networks 49a, which provide for the transfer of information between two nodes in path layer networks; and physical media layer networks 49b, which deal with the details of the transmission media. The path layer 48 networks support different types of circuit layers and bridges the circuit 47 and transmission 49 layers by providing logical connections between terminated node pairs. Each of these layers can be designed, activated, and altered independently from other layers. An important characteristic of the SDH (SONET) transmission systems is the capability of providing automated cross-connect functions at each multiplexing level.
The recent trends in ATM(SDH (SONET) broadband technology have led to high-speed fiber transport links, high-capacity network systems, and multimedia services, which trends have increased the importance of the efficient utilization of bandwidth with guaranteed Quality of Service (QoS). Unfortunately, these trends have also increased the vulnerability to network failures.
In the present state of development, most of the bandwidth management schemes deal with either SDH (SONET)/PDH networks alone, such as described for instance in "Dynamic Network Configuration Management" ICC '90, Vol. 2, pp.302.2.1-7 to G. Gopa, et al., or ATM networks, such as described in "Topology Design and Bandwidth Allocation in ATM Networks," IEEE JSAC,SAC-7(8), pp. 1253-1262 (1989) to M. Gerla, et al. These schemes propose either the integration of a single technology, e.g., a pure STM (Synchronous Transfer Mode) option or, eventually, a pure ATM option, in an integrated ATM and SDH (SONET) transport network. For instance, in an embedded ATM transport option shown in FIG. 2(a), the ATM cells are completely transparent to the SDH (SONET) network elements (NEs) with ATM cells being mapped to the concatenated mode of SDH (SONET) payloads by using conventional SDH (SONET) Network Elements 38a (NE). The SDH (SONET) NEs provide transport of both STM traffic 41 and additionally, the transport of ATM cells 51 from the customer ATM CPE (customer premises equipment) to the ATM switch and back to the customer ATM CPE. As shown in the network element view of FIG. 2(a), STM switch fabric 30 is used to cross-connect VC3 paths under STM management only, as indicated by element 35.
Utilizing the TMN SDH (SONET) model for layered transport, FIG. 2(b) shows how ATM service may be provided in the SDH (SONET) path layer 48. Particularly, the SDH (SONET) path layer is divided into two different paths layers: STM wideband 51 and STM broadband 52 that have been constructed in the existing SDH (SONET) networks by using SDH (SONET) cross connect systems or Add/Drop Multiplexers ("ADM") to provide transparent transport of ATM traffic. Switching of ATM traffic is performed by ATM edge switches located in the access or CPE network and ATM hub switching systems in the junction or interoffice network (not shown). An ATM Service Access Multiplexer (SAM) can be used at the edge of the public ATM network to provide ATM interfaces and adaptations for customer services to help reduce the transport inefficiencies associated with the conventional SDH (SONET) hierarchical tributary structures.
When there is very little ATM circuit traffic, the implementation of STM wideband path and STM cross connects is sufficient. As ATM traffic demand increases, however, there is a need to provide ATM path. It has been proposed in the reference to Tomonori Aoyama, Ikuo Tokizawa, and Ken-ichi Sato entitled "Introduction Strategy and Technologies for ATM VP-based Broadband Networks" I.E.E.E. J:S.A.C., Vol. 10, No. 9, pp. 1434-1447 (1992), that a pure ATM option will be the preferred network transport option for transporting both STM and ATM traffic.
It would be desirable to enhance network reconfiguration capability by providing network element capability to support three different paths STM broadband, STM wideband, and ATM VP, especially, with the perspective of guaranteeing QoS and favorable economics. Thus, it is important to examine both circuit and path layers in network evolution scenarios to minimize the cost and QoS degradation associated with the circuit emulation between STM and ATM networks.
There have been very few studies that address overall strategy of bandwidth management to utilize the strengths of both ATM and STM technology, and there currently exists the need for service providers to provide flexible, evolvable and cost-effective bandwidth management solutions.
It would be highly desirable to provide a layered bandwidth management system that facilitates network system and service evolution for emerging ATM transport technology and to develop a cost-effective evolution planning strategy.
Additionally, it would be desirable to provide a bandwidth management scheme that exploits the strengths of both STM and ATM technology to realize a more manageable and cost-effective network.